ImageLoad via Windows Update Auto Update Client

edit

ImageLoad via Windows Update Auto Update Client

edit

Identifies abuse of the Windows Update Auto Update Client (wuauclt.exe) to load an arbitrary DLL. This behavior is used as a defense evasion technique to blend-in malicious activity with legitimate Windows software.

Rule type: eql

Rule indices:

  • logs-endpoint.events.*
  • winlogbeat-*
  • logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Defense Evasion

Version: 7 (version history)

Added (Elastic Stack release): 7.11.0

Last modified (Elastic Stack release): 8.3.0

Rule authors: Elastic

Rule license: Elastic License v2

Investigation guide

edit
## Config

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.

Rule query

edit
process where event.type in ("start", "process_started") and
(process.pe.original_file_name == "wuauclt.exe" or process.name :
"wuauclt.exe") and /* necessary windows update client args to load
a dll */ process.args : "/RunHandlerComServer" and process.args :
"/UpdateDeploymentProvider" and /* common paths writeable by a
standard user where the target DLL can be placed */ process.args :
("C:\\Users\\*.dll", "C:\\ProgramData\\*.dll",
"C:\\Windows\\Temp\\*.dll", "C:\\Windows\\Tasks\\*.dll")

Threat mapping

edit

Framework: MITRE ATT&CKTM

Rule version history

edit
Version 7 (8.3.0 release)
  • Formatting only
Version 5 (8.2.0 release)
  • Formatting only
Version 3 (7.12.0 release)
  • Formatting only
Version 2 (7.11.2 release)
  • Formatting only